SQLAlchemy has no intrinsic issue with views but the thing that goes wrong with
views is that they perform very poorly when used with composition. that is, if
you take your view and use in a subquery, do some GROUP BY on it, do some LEFT
OUTER JOIN onto it, the performance plummets, because the view itself is
already pre-optimized to the complex query which it represents.
so if you are using SQLAlchemy and then adding lots of joinedload() to a query,
you would get a lot of LEFT OUTER JOIN onto your view and it might not be very
efficient from a DB server perspective. solution, dont use joinedload(), we
have other eager loaders namely selectinload() which put much less stress on
the query planner.
On Fri, Jun 16, 2023, at 10:15 AM, Dan Stromberg wrote:
> Hi.
>
> In https://pajhome.org.uk/blog/10_reasons_to_love_sqlalchemy.html it says:
>
> When performing highly complex queries, it is possible to define these
> with SQLAlchemy syntax. However, I find there's a certain level of
> complexity where it becomes easier to write SQL directly. In that
> case, you can define a database view that encompasses the complex
> query, and SQLAlchemy can map the view to Python objects.
>
> I spoke with my team lead about this practice, and he was open to
> trying it but said he had heard that SQLAlchemy may have problems
> using views.
>
> Does anyone on the list have anything to add here?
>
> Thanks!
>
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> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
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> http://www.sqlalchemy.org/
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http://www.sqlalchemy.org/
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